This invention relates generally to steam conditioning of feed grains and more particularly to a vertical steam chamber for such conditioning which resists plugging or bridging due to grain expansion and softening during conditioning.
Steam conditioning is an important part of processing for feed grains in preparation for flaking, or pelleting, or other forming operations. Such conditioning moisturizes, softens, and aids in sterilization of the grains prior to forming. It is fairly common for conditioning to be performed in vertical chambers in which the grain is fed from the top of the chamber and discharged from the bottom. Steam for conditioning is fed at the bottom of the chamber and at intermediate locations along the height of the chamber to provide a counterflowing steam environment within the chamber. Both circular and rectangular cross sections can be found in vertical conditioning chambers presently available. In addition, both tapered and straight sided chambers can be found. Straight sided chambers have either cylindrical or rectangular geometries having the same cross section at both top and bottom of the chamber. Tapered chambers have conic or trapezoidal geometry which is larger at the bottom than at the top.
During operation, the grain being conditioned expands and softens due to the increase of moisture content and temperature induced by the steam conditioning. As a consequence, there is a tendency for the grain to jam or plug the conditioner due to friction and bridging of the expanding softening grain. This tendency to jam the conditioner is reduced somewhat by the tapered conditioner design. The corners of the rectangular cross section chamber, however, often provide a sufficient increase in friction to initiate bridging which leads to jamming. Thus, the tapered chamber having a round cross section is significantly to be preferred above either the straight or tapered chamber of a rectangular cross section, due to elimination of the corner effect.
Although it is functionally preferred, the tapered round conditioning chamber must overcome the obstacle to its employment imposed by the cost of manufacture of such chambers. Fabrication of a round tapered chamber requires development of large complicated plate forms in order to form the required conic sections. In addition to the manufacturing difficulty, the cost of scrap material generated during plate cutting adds significantly to the total cost of the chamber structure.
The foregoing illustrates limitations known to exist in present devices and methods. Thus, it is apparent that it would be advantageous to provide an alternative directed to overcoming one or more of the limitations set forth above. Accordingly, a suitable alternative is provided including features more fully disclosed hereinafter.